Needsdecaf

So I went into this eyes wide open. Knew about the stumble from this wonderful forum and when I was looking for my 991, I was desperate to avoid it. When I found the car I eventually bought in North Carolina, I even had the dealer send me videos of the car accelerating between 2k and 3k. When I went to pick up my car, the dealer knew what I was worried about and I told him that I would t buy the car if I detected the stumble. To my relief, it wasn't there.

Bought my car with 29,795 miles on it. Drove it home almost 1,300 miles. That was September of 2016. The car now has about 33,500 miles on it. It's been driven every week I've owned it, at least once. Usually 3 - 4 times.

Much of my driving is low speed driving. With the MT, the speeds that I travel puts me in the 2k to 3k range quite a bit. I've never observed anything untoward.

Recently, though, I started noticing something. Something a bit "not smooth". I wasn't sure if it was my driving, the clutch, etc. I've been teaching my wife to drive the clutch so my first thought was that she glazed the flywheel, burnt out the clutch, etc. however she tends to jerkily engage, not ride it, and I've never smelled burnt clutch after she's driven it. I've done several pulls to check for clutch slip and can't detect any.

I thought of the stumble. I've been gently driving in normal and sport between 2k and 3k in second and third, probably a quarter throttle and i can feel it. Ever so slight, there is a brief hesitation / surge right around 2,800 RPM. It's present in second and third. Can't feel it in fourth and can't be sure in first, but it's there.

I'm sick. It's so slight, no dealer is ever going to think it's an issue. But it's there. I can feel it. And in reading the thread on 6 speed, it seems as if there is still no cure.

Anything else it could be? Has anyone just had it appear like this? I know without a doubt it was not there before.

DerekS

Maybe the stumble you feel is actually a slipping clutch. My first 911 needed one around 35k miles.

Needsdecaf

That was my first thought. But it happens under such gentle load, I don't think so. I can roll on at 5k RPM and have zero issues.

Dewinator

When you have cruise control on in 7th on the freeway at like 70 or something, is there a slight up and down wavering of the RPMs like the car is having to work the throttle just a touch to hold the speed?

fast1

I agree about the clutch. If you have a problem with moderate pedal pressure, it would be far worse under heavy acceleration. Putting my psychologist hat on, just wondering if you would have detected the hesitation if you weren't looking for it. I can still recall a student in med school who was certain that he had every malady that he studied.

Needsdecaf

That's the thing though; it wasn't there when I was looking for it 9 months ago. Now that I'm not looking for it, it appears.

Needsdecaf

Not that I could tell. Had it on the highway last night, but honestly I don't get on the highway that much in this car.

DerekS

That's why I am suspecting the clutch over the stumble. The stumble doesn't come and go, does it? It's just there and never leaves.

9914s

My stumble started after two years of ownership.

Dewinator

Hmm ok. My understanding was the true stumble occurs even at max throttle like that Cayman video, mine was more of an unsmoothness/wavering at lower throttle settings when my throttle valve was having problems.

Needsdecaf

Crap. Care to share details?

rk-d

I've read that it could be a variocam transition phenomenon, bad intake valve or a software issue. Do you have PSE? Someone had an issue with their control module and the PSE. Sounds like dealers don't really have much to offer b/c their diagnostics don't indicate an issue and owners are told that this is just a characteristic of the motor. Some people have had better luck with indy's.

I hate to say it, but if it bothers you this much - you might need consider selling it? Particularly if there is no solution after 4 years of this being reported and dealers indicating that this is normal behavior.

stealthboy

If it is the dreaded stumble, I have pity on your soul. It will consume you.

4 years in and still no solution for me. There is a rougher hesitation when accelerating with moderate throttle in the 2-3K RPM range, and a more distinct stumble at 2800-3000 which in my opinion is definitely a VarioCam Plus transition point.

The official word from Porsche is that this is "normal". My latest development was taking it to an independent mechanic (who has been rebuilding 911 engines for decades) and he said "that is not normal".

mmaturo

I have it...I just give up on using the car like I should be able to. Pulling out of a drive on to a road with traffic coming I now hesitate or wait since I do not know what the car will do when I mash the pedal. 9 out of ten it will not have the power and stumble. between that and the rattles/squeaks I have in my cabin I am over my particular car. I have complained. it was called normal. they did a couple of reflashes that seemed to help for a short bit but its fully back now '14 C2S PDK w 52K miles.

Needsdecaf

I sure hope it's not.


Mine is definitely not that bad. You would never drive it and think there was any point that it lacked power. There is just that slight hiccup. If I mash the gas, it's practically undetectable.